Ban overwhelmingly won an informal poll of the UN Security Council on Monday, making his selection later this month all but certain.

"We've been saying all along that (the next candidate) should come from Asia, so it's good," Kyodo News agency quoted Aso as saying when asked about Ban's eventual victory.

Other Japanese officials have been even less direct about Tokyo's support for Ban. Deputy Chief Cabinet Secretary Hakubun Shimomura told reporters that Japan supports an Asian to become next UN chief, but refused to endorse Ban.

"Our basic position is that the next secretary general should be selected from Asia," Shimomura said, refusing to comment on any particular candidates.

The discussion coincides with moves to arrange a summit between Japanese Prime Minister Shinzo Abe and South Korean President Roh Moo-hyun.

Japanese news reports say the meeting could come as soon as early next week.